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James Webb Space Telescope | About the JWST
- Evie Wilson
- Feb 21, 2022
- 7 min read
Updated: Aug 23, 2023
On December the 25th 2021, NASA launched the world’s largest observatory to date: the James Webb Space Telescope (JWST). Despite the tennis court-sized craft's 344 single points of failure (SPOFs), a fault at any one of which would cause total failure, the deployment of the telescope was successful. It has now reached its home at L2 — a gravitationally stable spot known as a Lagrange point, over 1 million miles away from Earth.
Inspired by an iconic image of distant galaxies shimmering against an endless sea of black—taken from JWST’s predecessor, the Hubble Space Telescope — the team at NASA embarked on a mission to try and study even further back into the universe’s origins. How far back? 300 billion light years, to be precise. The project spanned decades and spearheaded numerous technological advancements — but what's come of it? Let's review the JWST's progress so far.
What is the James Webb Space Telescope?
The James Webb Space Telescope, also known as JWST or the Webb Telescope, is the Hubble Space Telescope's successor. Defined by NASA as "an infrared observatory", the telescope launched with the aim of building on the findings of the Hubble Space Telescope, and NASA says it will "study every phase in the history of our universe, ranging from the first luminous glows after the big bang, to the formation of solar systems capable of supporting life on planets like Earth, to the evolution of our own solar system".
Infrared technology
Ever since the Big Bang, the universe has been expanding. This means that older galaxies are moving away from us at an exponential pace. As they move away, a phenomenon called redshift pushes the wavelengths of light out of the visible spectrum and into the infrared spectrum. The James Webb Space Telescope is an infrared telescope, which essentially means that it sees with light which is invisible to human eyes, allowing it to see through otherwise opaque dust in the universe to view hidden stars and planets.
The JWST's predecessor, the Hubble Space Telescope, had limited infrared imaging capabilities, only detecting a small portion of these wavelengths. This means that in the past, our ability to see the oldest parts of the universe in high detail was limited, as these galaxies and planetary bodies are redshifted far beyond the visible light spectrum. The JWST, however, is equipped to see galaxies deep in the infrared, and so allows us to capture images of galaxies over 13 billion years old!
Technical requirements for the JWST
As you can imagine, getting a technological marvel as delicate and intricate as the JWST into L2 orbit isn’t any small feat, let alone making it function flawlessly in the extremes of space. To do this, an abundance of new technologies and engineering innovations were required to develop and deploy the telescope.
Unfold in space
The sheer size of the JWST means it had to fold up until it was in space. Over the course of its ascent to L2, the 18 honeycomb-shaped mirrors of its upper section had to unfold and fan out, forming a single mirror over 6 metres in size. According to JWST’s Optical Telescope Element Manager, Lee Feinberg, each of the 18 Hexagonal mirror pieces of the upper section had to align within one five-thousandth the width of a human hair.
Unimpaired function in the extreme environment of space
The telescope requires extreme temperatures to function. Whilst its upper sun-facing portion has to remain consistently at 85℃, the other side is kept at approximately −233°C. To maintain these vastly different temperatures, the two sections are separated by a precisely positioned five-layered sun shield, each successive layer cooling the region beneath.
Block signals interference
To block out infrared background ‘noise’, the JWST had to utilise the world’s coolest element, helium, for its mid-infrared instrument’s cryocooler (a refrigerator designed to reach cryogenic temperatures). The technology surrounding the mid-infrared instrument, or MIRI, marked a huge stepping stone in the field of astronomy. The longer the wavelength of infrared, the cooler the detector needs to be. Given the JWST's ambitious 14 billion year observation path, its detector system has to stay at less than 7 kelvin to operate efficiently, −266°C!
Where is the James Webb Space Telescope now?
Unlike the Hubble Space Telescope, the JWST does not orbit the Earth, but rather the sun; it is currently at the second Lagrange point (L2) a million miles from Earth. Lagrange points are described by NASA as points where "the gravitational pull of two large masses precisely equals the centripetal force required for a small object to move with them" — this means that any objects sent there, stay there.
When it comes to astronomy, L2 is the perfect spot, as a spacecraft there can communicate with Earth while also keeping the Sun behind it (which equals solar power), and most importantly, accessing a view of deep space. For a telescope, this spot is pretty perfect.
What will the James Webb Space Telescope be observing?
Pushing the boundaries of human ingenuity, the James Webb Space Telescope stands as the most impressive machinery that NASA has perhaps ever created. But what has it actually set out to observe?
Exoplanets
Exoplanets are planets that exist outside of our Solar System. One branch of JWST’s observing programmes will be focusing on the atmosphere of exoplanets, and if any potential foundations of life exist on these bodies. One way that this information will be gathered is called the Transit Method — this is essentially where we observe the light that comes from a star, so that we can see when a planet passes in front of it.
The JWST is also capable of spectroscopy, which consists of measuring the intensity of light at different wavelengths, as well as taking coronographic observations, which involves using a telescopic attachment that blocks out direct light emitted from stars, unveiling nearby objects in the process.
Very, very distant galaxies
As fantastic as The Hubble Telescope is, it isn’t able to detect the first galaxies. The JWST is optimised with unparalleled infrared technology to detect faint infrared light from billions of years in the past, looking at a part of space that we've never seen before.
Compared to its predecessor, the JWST has a fifteen times wider field of view on its main camera and collects six times the light — capabilities that could get us closer to establishing the origins of the universe than we've ever been. In order to make these discoveries, the JWST’s camera will stare deeply into one patch of sky for extended periods of time, gathering as much light and information as possible.
Dark matter and dark energy
Dark matter and dark energy remain the greatest mysteries in the realm of astrophysics. These terms essentially refer to that which's existence is determined by mass rather than light — we can't see it, but we know it's there.
The team at JWST aims to unravel some of the truths around dark matter and energy, potentially bridging the gap between Hawking’s decades-old notions and a deeper understanding of antimatter. They hope to achieve this by observing disturbances in what is known as gravitational lensing. These images will seek to make the invisible, visible.
Gravitational patterns
Much like a fun-house mirror, space and time can be curved and warped. Since gravity bends the path of light, and light travels through spacetime, light can dip and curve in the presence of massive objects: this process of distortion is called gravitational lensing.
The JWST aims to detect the nature of gravitational lensing patterns from distant galaxies, furthering our understanding of both the structure and expansion of the universe.
Primordial black holes, expanding on Hawking's research
One major theory concerning the nature of dark matter’s role in the Big Bang comes from Hawking’s primordial black hole research — the idea that dense regions that existed in the hot and hyper-compact early universe became the first black holes.
The JWST may serve to prove or completely debunk this idea, as well as competing alternatives; for instance, the theory about black holes resulting from the collapse of stars.
Many astronomy experts are keen to see whether or not black holes have existed since the beginning of time, or whether they came to fruition only after the first generation of stars died out. If the JWST manages to detect the first light of the universe, and thus the stars that formed mere moments after the Big Bang, this question may be answered at last.
What has the James Webb Space Telescope seen so far?
The JWST has been in space for over a year, and it's already captured some incredible images. The above image shows a cluster of galaxies surrounded by older, more distant galaxies. Some of the galaxies in this picture are over 13 billion years old!
This picture is what is referred to as the 'Pillars of Creation', a photograph taken by the Hubble Space Telescope of gas and dust in the Eagle Nebula, over six thousand light-years from Earth. The James Webb Space Telescope has since captured an even higher quality image of the Pillars of Creation, visible below.
A recent image captured by the JWST is of the galaxy NGC 5068. Much of the gas and dust involved with star and planet formation is fully opaque to the Hubble Telescope due to its visible-light limitations. However, the JWST is equipped with a Mid-Infrared Instrument (MIRI) and a Near-Infrared Camera (NIRCam), which, according to NASA, make it incredibly well-suited to capture the processes influencing star formation.
These instruments have enabled astronomers to see through NGC 5068's opaque dust clouds and "capture the processes of star formation as they happened". The below image clearly showcases the JWST's capabilities, giving us a previously unseen look into NGC 5068.
Dark matter is one of the biggest mysteries faced by today's scientists. By helping scientists understand how galaxies have changed over time, the JWST will begin to help them understand some of the properties of dark matter, which is a huge step in understanding what it actually is.
As its images of NGC 5068 make clear, the Webb Telescope's capabilities are unlike anything we have seen before, and it seems that if there's any technology that will help us better understand dark matter, the JWST is by far our most likely candidate.
For more about the science behind the shots, head over to our in-depth article on the topic!
The future of the JWST
Evidently, the Webb Telescope is off to a great start. It has already captured images of previously unseen galaxies and it will undoubtedly continue to make ground-breaking discoveries.
The telescope is only one year into its expected twenty-year life; at the very least, it'll continue to capture galaxies and planets we never thought we'd be able to see. If we're lucky, however, it could revolutionise our understanding of the origins of our universe.